In a dynamic rigid disk storage device, a rotating disk is typically employed to store information. Rigid disk storage devices typically include a frame to provide attachment points and orientation for other components, and a spindle motor mounted to the frame for rotating the disk. A read/write head is usually provided as part of a "head slider" to be positioned in close proximity to the rotating disk and to enable the writing and reading of data to and from the disk surface. In the case of a magnetic storage device, a magnetic read/write head is employed to create and read magnetic domains to and from the disk surface.
The head slider is supported and properly oriented in relationship to the disk by a head suspension that provides forces and compliances necessary for proper head slider operation. As the disk in the storage device rotates beneath the head slider and head suspension, the air above the disk also rotates, thus creating an air bearing which acts with an aerodynamic design of the head slider to create a lift force on the head slider. The lift force is counteracted by a spring force of the head suspension, thus positioning the head slider at a desired height and alignment above the disk which is referred to as the "fly height."
Typical head suspensions for rigid disk drives include a load beam and a flexure. The load beam normally includes a mounting region at a proximal end of the load beam for mounting the head suspension to an actuator of the disk drive, a rigid region, and a spring region between the mounting region and the rigid region for providing a spring force to counteract the aerodynamic lift force generated on the head slider during the drive operation as described above. The flexure typically includes a gimbal region having a slider mounting surface where the head slider is mounted and thereby supported in read/write orientation with respect to the rotating disk. The gimbal region is resiliently moveable with respect to the remainder of the flexure in response to the aerodynamic forces generated by the air bearing and to permit the head slider to follow disk surface fluctuations.
In one type of head suspension the flexure is formed as a separate piece having a load beam mounting region which is rigidly mounted to the distal end of the load beam using conventional means such as spot welds. Such head suspensions typically include a load point dimple formed in either the load beam or the gimbal region of the flexure. The load point dimple transfers a predetermined load generated by the spring region of the load beam to the flexure and the head slider to counteract the aerodynamic force generated by the action of the air bearing against the head slider and to define the desired fly height. Such a load point dimple also provides clearance between the flexure and the load beam, and serves as a point about which the head slider can gimbal in pitch and roll directions so as to follow fluctuations in the disk surface.
Due to the close proximity of the head slider and the rotating disk at the fly height of the head slider, it is important that the head slider be properly positioned over the disk at the desired fly height. The position of the head suspension and head slider, also known as the static attitude, is calibrated so that when the disk drive is in operation the head slider assumes an optimal orientation at the fly height. It is therefore important that the static attitude of the head suspension be properly established. Toward this end, the flexure must be mounted to the load beam so that misalignments between the flexure and the load beam are minimized since misalignments between the load beam and flexure may introduce a bias in the static attitude of the head suspension and the head slider. Misalignments in the head suspension components also affect the alignment of the load point dimple in relation to the head slider when the head slider is mounted to the head suspension. Misalignments between the load point dimple and the head slider may cause a static attitude torque to be exerted on the head slider, and thus affect the orientation of the head slider at the fly height.
To assist in the proper alignment of the flexure to the load beam and the proper alignment of the head slider to the head suspension, the load beam and the flexure of a head suspension each typically include a circular tooling hole having a pre-determined diameter. These tooling holes facilitate alignment of the flexure on the load beam through the insertion of a tooling pin in both of these holes prior to mounting the flexure to the load beam, thus concentrically aligning the tooling holes. The flexure can then be spot welded or otherwise attached to the load beam, and the resultant head suspension will be aligned based on the accuracy of the positioning and sizing of both tooling holes. Thus, to obtain accurate alignment, strict tolerances for the tooling holes must be maintained.
The tooling holes in the flexure and the load beam are also used to facilitate the mounting of the head slider to the head suspension. A tooling pin is inserted in the flexure and load beam holes later in the assembly process to hold the head suspension in place during the head slider mounting procedure. The location of the load point dimple on the head suspension is determined, and the slider is aligned and mounted to the head suspension at a desired location. Thus, to obtain accurate alignment of the head slider, it is important that the flexure be accurately aligned and mounted to the load beam of the head suspension so that the load point dimple is correctly oriented on the head suspension.
The mounting of an individual flexure on an individual load beam using an alignment pin is very time intensive. Thus, carrier strip assemblies have recently been employed to more efficiently manufacture head suspensions. In a carrier strip manufacturing process, multiple flexures are formed while attached to a first carrier strip assembly, and multiple load beams are similarly formed while attached to a second carrier strip assembly. Reference holes in the carrier strip assemblies are then used to align the plurality of individual load beams over a corresponding number of flexures, and the flexures are conventionally mounted on the load beams. In this manner, head suspensions can be more efficiently manufactured. Because a pin is not used to align the tooling holes in the individual flexures and load beams, however, it sometimes occurs that even with the individual flexures and the individual load beams aligned by this method, the flexure tooling hole and the load beam tooling hole might slightly overlap. Any overlap in the tooling holes, however, will create an undersized hole that may prevent a tooling pin from later being inserted through the holes, for example, during the mounting of the head slider to the head suspension.
It is important to be able to accurately and efficiently determine any misalignments between the flexure and the load beam of a head suspension. A determination of the misalignment will indicate whether the head suspension is within predetermined manufacturing tolerances. In addition, a determination of the misalignments allows for such misalignments to be compensated for during the mounting of the head slider to the head suspension.